Visibility Challenges Industrial Control System Security: Survey

Keeping tabs on the control systems at critical infrastructure companies is challenging organizations at a time when attackers are circling.

In a new survey of from the SANS Institute, 32 percent of respondents that admitted having experienced a breach weren't sure how many times they had been breached. In addition, 44 percent were unable to identify the source of the attack.

The results came from a survey of 314 respondents from across several industries that actively maintain, operate or provide consulting services to facilities maintaining industrial control systems. According to the report, 42 percent of respondents said outsiders are the top threat to industrial control systems (ICS), while 73 percent outside attackers were in the top three. Internal threats came in second and were named by 49 percent as one of the top three threats.

Monitoring inside a control systems network is challenging for a number of reasons, Derek Harp, business operations lead for the Industrial Control System (ICS) programs at SANS and co-founder and executive chairman for NexDefense, told SecurityWeek.

"The existing ICS protection model places a great deal of focus on perimeter protection through logical segmentation," Harp said. "Cyber threats that are able to transcend that protection by riding along on media or taking advantage of remote connections are difficult detect once inside. Most tools developed for the purpose are for IT environments and are not optimized and can pose a reliability risk for ICS hosts or networks. This can slow down or interrupt control system traffic, alert or act on false positives, or even be misinterpreted by control devices and cause operational disruptions such as unexpected shutdowns. This has been observed in both lab and live operational settings."

ICS security staff are doing everything they can, but the tools to safely monitor, examine and analyze what's happening at the network level are pretty new to the market and not widely implemented yet, he added. Without these, malware may successfully hide and spread without detection so long as it doesn't impact the normal operations of control devices, he said.

According to the report, general-purpose computing assets such as human–machine interfaces [HMI], servers and workstations running commercial operating systems are considered to be at greatest risk of compromise by 44 percent of respondents. The runner-up, chosen by 14 percent as their primary concern, is the connection of office networks to the internal systems.

Another commonly cited challenge was the integration of IT into once-isolated operational technology (OT) systems such as ICS. Just 29 percent of respondents have started implementing a strategy to manage that convergence securely. Thirty-six percent said they were developing a strategy, while 18 percent had no strategy at all and doesn't plan to develop one.

"The convergence of IT and OT is introducing all of the security concerns of the IT world into the previously distinct world of control systems," said Bengt Gregory-Brown, consultant to the SANS ICS program and the principal analyst at Sable Lion Ventures, LLC. "For over fifteen years we've been connecting more and more control devices up to Ethernet/IP networks and hooking up equipment running general purpose operating systems such as Windows XP. By doing so we are making our ICS environments susceptible to the same threats as the computers sitting on our desks. Stuxnet was designed around this fact."